Natural and synthetic fabrics and particularly synthetic, non-woven fabrics have been used extensively in the production of light-weight components for healthcare and sportswear products as well as components for transportation vehicles, including airplanes and spacecraft. Rendering fabrics, in general, and particularly non-woven ones, antibacterial, using conventional and novel processes, has been called for by textile manufacturers and users. These circumstances and recent developments of the surface phosphonylation technology or permanent attachment of reactive phosphonate groups on synthetic polymers and established ability of iodine to form an antimicrobial agent when complexed with polyvinylpyrrolidone provided an incentive to look for novel approaches to produce new fibrous substrates that display antimicrobial (or antibacterial) activities, preferably over prolonged periods of time through modulating the release of the antimicrobial (or antibacterial) agents.
In one aspect of the present invention is concerned with introducing and controlling the release of known and novel forms of broad-spectrum antibacterial agents in unmodified or surface-phosphonylated fabrics and particularly non-woven polypropylene fabrics (NPPF) and non-woven Nylon 6 fabrics (NNF). More generally, the present invention is concerned with rendering a variety of non-woven and woven fabrics and knitted fabrics, including those made of polyethylene, polyesters, nylons, and acrylic copolymers, antimicrobial.
Surface phosphonylation of polymeric substrates is disclosed in U.S. Pat. No. 5,491,198 to Shalaby, et al., which is hereby incorporated herein by reference. In accordance with the present invention, it has been discovered that both unmodified and surface-phosphonylated fabrics can be treated with antimicrobial agents in a manner which allows for the incorporation of controlled release of those agents. Thus, with surface phosphonylated fibers, ionic conjugation of antimicrobial agents to the functionalized surfaces (following the appropriate post-treatment to create anionic or cationic binding sites to cationic and anionic agents, respectively) allows for incorporating and controlling the release of the antimicrobial agents and imparting antimicrobial activity over prolonged periods during fabric end-use.
In another aspect of this invention, non-modified fiber surfaces (such as those of polypropylene, polyethylene, and similar fibers used in the textile industry) containing antimicrobial agents such as triclosan (which has a high propensity to sublime or evaporate from the fibers when used as a surface auxiliary) is used in a practically non-volatile salt under usual end-use conditions. It is also the object of this invention to provide a method for introducing the triclosan salt, as well as similar agents, into the subsurface of the fiber to control its release and allow for prolonged antimicrobial activities.
In another aspect of this invention, the demonstrated ability to complex iodine with polyvinylpyrrolidone in solution to produce an effective antimicrobial liquid was extended to develop novel solid polymeric substrates displaying antimicrobial activities. More specifically, these solid substrates are fibers made of polyamides, such as nylon or polymers other than polyamides, but grafted with amide-bearing chains. These grafted polymers are capable of complexing with iodine to modulate its release and hence, produce fibers with prolonged antimicrobial activity. More specifically, the polyamide fibers comprise Nylon 6 and the grafted fibers comprise polypropylene, polyethylene, polyester, and cellulosic fibers.
Of the many available antibacterial agents, those discussed below were selected to (1) be active against both gram-positive and gram-negative bacteria; (2) provide a diverse mode of action; (3) explore novel forms for modulating their release; and (4) allow the use of the most suitable agents for NPPF or NNF.
Chlorhexidine (CXD)xe2x80x94Chlorhexidine is available as a salt of gluconic, acetic acid, or hydrochloric acid. The free base is a bis-guanidine with strong bacteriostatic activity [Davies, G. e., Brit. J Pharmacol., 9, 192 (1954)]. It is very basic and forms salts with most acids quite readily. It is sparingly soluble in water. However the diacetate is soluble in water and alcohol. The aqueous solution decomposes when heated to above 70xc2x0 C. The salts of CXD are used as an antiseptic or disinfectant. It is well established, clinically, that CXD gluconate provides antimicrobial effects against a wide range of microorganisms including gram-positive and gram-negative bacteria. It is indicated for surgical scrub, skin wound cleanser, and pre-operative showering.
Benzalkonium Chloride (BAC)xe2x80x94This is a mixture of alkyldimethylbenzylammonium chlorides (the alkyl groups consisting of C8H17 to C18H37 groups) with established antimicrobial activity [Gump, W., in KIRK-OTHMER Encyclopedia of Chemical Technology, Vol. 7, Wiley, 3rd Ed., 1979, p. 815]. It is a cationic surface active agent, available as an amorphous powder that is soluble in water and alcohol. It is a rapidly acting anti-infective agent with moderately long duration of action. BAC is active against bacteria, fungi, protozoa, and some viruses. Solutions of BAC are bacteriostatic or bactericidal according to their concentrations. BAC complexes combine readily with anionic detergents.
Mupirocin (Pseudomonic Acid A)xe2x80x94Mupirocin, a topical antibacterial, is produced by fermentation of the organism Pseudomonas fluorescans [Chain, B. and Mellows, G., Chem. Commun., 847 (1974); Fuller, A. T. et al, Nature, 234, 216 (1971)]. The total synthesis of the (xc2x1)-form was reported by Snider and coworkers [J. Org. Chem., 48, 303 (1983)]. Mupirocin is soluble in alcohol. It inhibits bacterial protein synthesis by reversibly and specifically binding to bacterial isoleucyl transfer-RNA synthetase. Hence, mupirocin shows no cross-resistance with gentamicin and tetracycline (Casewell, M. W. and Hill, R. L. A., Antimicrob. Chemother., 19, 1 (1987); Ward, A. and Campoli-Richards, D. M., Drugs, 32, 425 (1986)]. The following gram-positive bacteria are susceptible to mupirocin in vitro [Casewell, M. W. and Hill, R. L. A., Antimicrob. Chemother., 19, 1 (1987); Antimicrob. Chemother., 15, 523 (1985)] S. aureus, S. epidermidis and S. pyogenes. Clinically, it is indicated for the treatment of impetigo due to S. aureus and S. pyogenes. 
Zinc Salts and Complexesxe2x80x94A number of zinc salts and complexes have been noted to have antiseptic or antibacterial activities. Zinc acetate is used in veterinary medicine as an antiseptic agent [Budavari, S. (Ed.), The Merck Index, 20th Ed., Merck and Co., Inc., Whitehouse Station, N.J., 1996]. An aqueous solution of zinc sulfate is used as a mild astringent for temporary relief of minor eye irritation. Zinc propionate is used on adhesive tape plaster for irritation caused by fungi and bacterial action. It is also used topically as an antifungal agent [Budavari, S. (Ed.), The Merck Index, 20th Ed., Merck and Co., Inc., Whitehouse Station, N.J., 1996]. Bacitracin zinc complex (prepared by the action of zinc salts on bacitracin broth) is a water-soluble powder that contains about 7 percent zinc and is used as an antibacterial agent (Hodge, L., U.S. patent (to CSC) U.S. Pat. No. 2,803,584 (1957)].
Triclosan (TSN)xe2x80x94This is a phenolic compound derived from chlorinated phenyl oxide. It is a crystalline compound that is insoluble in water, but readily soluble in alkaline solutions and organic solvents. It is used as a bacteriostat and preservative for cosmetic and detergent preparations (Model, E. and Bindler, J., U.S. patent (to Geigy) U.S. Pat. No. 3,629,477 (1971); Savage, C. A., Drug. Cosmet. Ind, 109(3), 36,161 (1971)]. Over the past few years, TSN has been recognized by the film and textile industry as a highly effective bacteriostatic agent against a wide range of gram-positive and gram-negative bacteria.
Complexes of Polyamides with Iodinexe2x80x94The most common complex of iodine with polyamide is that containing polyvinyl pyrrolidone (or povidone). The complex is known as povidone-iodine (Shelanski, S. J., Int. Coll. Surgeons, 25, 727 (1956)]. It is water soluble and contains 9 to 12 percent available iodine. It retains iodine""s bactericidal activity, but less potently. The complex is also soluble in alcohol. It is has been applied in several formulations as a topical anti-infective agent, including those used as surgical scrub. Iodine preparations, in general, are of common use for their broad microbicidal spectrum against bacteria, fungi, viruses, spores, protozoa, and yeasts.
The invention may be further understood by reference to the following examples, which are provided for the purpose of representation, and are not to be construed as limiting the scope of the invention.